An elastic articulation of the type described above is known from German Gebrauchsmuster No. 6,606,532. Such elastic articulations, in which the inner part comprising a rubber/metal part and the rubber body is thrust into the outer part and held therein by axial clamping are suitable for mass production. The axial clamping of the rubber body is relatively simple to accomplish, in comparison, for example, to a known radial clamping of the outer part on all sides.
In the known elastic articulation as described, the arrangements on the outer peripheral surface of the elastomeric body for enhancing the frictional adherence typically are grooves that are provided axially or peripherally on the said peripheral surface. The depth of the grooves typically amounts to one-third of the thickness of the rubber. Thereby, according to information in the above-mentioned Gebrauchsmuster document, the rubber is moved perpendicularly in compression as well as tangentially to the grooves, whereby there is supposed to be a more favorable uniform distribution of compression with an advantageous groove design, and thereby an improved frictional adherence between the rubber body and the outer part. However, it has been found that these structural arrangements in known elastic articulations did not invariably lead to an adequate increase in frictional adherence. In particular, when there is strong axial stressing and clamping of the annular parts, the frictional adherence only allows an insufficient angle of rotation of the elastic articulation. When the maximum permissible angle of rotation is exceeded, the rubber body slides in the outer part, with pronounced abrasion. Accordingly, the known elastic articulations are believed to not have adequate fatigue strength, functional reliability or life expectancy, in line with modern requirements. It is also to be observed that because of the "grooves" that extend relatively deeply into the rubber, there are disadvantageous notching stress peaks in the known elastic joints.
The present invention is directed to the problem of creating a simple and efficient elastic articulation, coupling or the like that avoids many of the drawbacks of the known elastic joints and that is more simply and inexpensively mass produced, and having improved frictional adherence between the elastomeric body and the outer part, and hence an enlarged maximum angle of rotation, and improved fatigue strength.
This problem is solved in an elastic articulation of the type here involved in that, according to the invention, the outer peripheral surface of the elastomeric body has a fabric of solid material embedded in it, whereby the fabric together with the elastomeric body can be axially stressed and clamped. The fabric is preferably of metal wire oriented such that the meshes run essentially diagonally to the cylinder axis. In other words, the fabric can be in the nature of a wire screen, with the individual wires oriented diagonally to the cylinder axis. In accordance with a particularly advantageous embodiment of the invention, the fabric extends over the entire peripheral surface of the elastomeric body. It will be understood, of course, that in the context of the present invention, the term "fabric" also denotes a grid formed from the wire material.
The invention solves the problem to which it is directed in an optimum manner with very simple means. A fabric with meshes or wires that run essentially diagonally to the axial direction of prestressing is yieldable with increase of the diameter of the fabric sleeve upon axial clamping of the annular parts at the end faces of the elastomeric body and fabric sleeve, in contrast to a fabric having its meshes in an axial-radial orientation. Therefore, the fabric in accordance with the instant invention moves particularly evenly onto the outer part. As a result, there is an especially good frictional adherence between the elastomeric body and the outer part, substantially uniformly over the whole periphery, which makes possible a correspondingly large maximum admissable angle of rotation of the elastic joint. In comparison to the elastic articulation known from German Gebrauchsmuster No. 6,606,532, there is a given maximum angle of rotation according to the invention with substantially less axial clamping stress, or with a given axial clamping stress the maximum angle of rotation in the elastic articulation according to the invention is greater than in the case of the known joint. When the maximum permissable angle of rotation is exceeded, there is a practically abrasion-free sliding between the peripheral surface of the elastic body with the fabric, and the metallic outer part. Thus, the elastic articulation according to the invention has good fatigue strength, functional reliability and life expectancy. The application of the fabric on the surface of the rubber elastic body is simple and inexpensive even in mass production. Since the fabric is embedded uniformly in the surface of the elastic body, there are moreover practically no notching stresses therein.
From another publication, German Pat. No. 2,520,947, it is known in principal, in an elastic articulation with a structure generally like that of the devices here involved, that metallic ring inserts running axially can be disposed in the rubber. These rings, to prevent axial deformation in axial clamping of the rubber, do not extend over its whole axial extent, and are axially and radially staggered. With this known construction, which in no way affords the advantages of the present invention, there is supposed to be frictional adhesion between the rubber body and the inner part as well as between the rubber body and the outer part. Additionally, this known elastic joint is expensive and is poorly applicable to mass production, and furthermore the metallic inserts must be secured particularly against axial withdrawal. The publication could thus contribute nothing to the solutions achieved by the present invention.
From German Pat. No. 1,955,308, it is known in principal that an elastically or plastically deformable sheet sleeve with uniformly distributed perforations could be provided, whereafter an outer part would be applied about the sheet sleeve. This known elastic joint is quite different from the present invention, and is not finished by axial clamping of the rubber body, but rather by radial compression all around. For this, V-shaped notches with their tips directed toward the inner part are provided in the rubber, which produces pronounced notching stresses. In addition, as previously mentioned, a radially compressed elastic joint of this kind is relatively more cumbersome in manufacture, and thus lends itself less well to mass production. Another difference with respect to the instant invention lies in the fact that in the known articulation, supplementary perforated sheet sleeves have to be set into the rubber.
Advantageously in the elastic articulation according to the invention, utilizing a metal wire fabric, the width of the meshes, that is, the openings formed by the wire grid, is at least one millimeter, and the wire thickness advantageously is at least 0.2 millimeters, preferably 0.5 millimeters.
An especially advantageous construction results if, according to another characteristic of the invention, the annular clampable parts applied to the end faces of the rubber elastic body are disposed in the region of the adjacent faces of the fabric. This ensures that the fabric together with the rubber elastic body will be uniformly compressed axially.
Exemplary preferred embodiments of the invention are described in detail below with reference to the appended drawings.